The invention relates to a flexible shipping bag formed by sewing together edges of at least one textile panel having a full-thickness region as well as warp and weft filaments, and along at least one of the selvages of the textile panel is provided with a partial-thickness region. The invention further relates to a method for producing a reinforced selvage of a is textile web.
In the production of a so-called “big bag” or “FIBC” (Flexible Intermediate Bulk Container), a flexible woven textile is generally used. Such textile woven materials are known, and can be produced on flat or circular weaving looms. Accordingly, one refers to flat or circular woven material. Woven material produced in this way has the generally known weaving pattern with crossing weft and warp filaments. However, the actual weave used has minimal bearing on the present invention.
In the production of the above-described shipping bag, textile panels of the textile woven material have to be sewn together. Taking into account that the shipping bags are designed to withstand considerable stress of for example 1000 kg to 5000 kg, it is obvious that the textile panels being used must be highly resistant to the woven material ripping at the seams. For this reason, it is known to provide the textile woven material being used with reinforced selvages.
If the textile woven material is produced on a flat loom, it is known to create a so-called Sulzer edge. The weft filaments are thereby folded over and then inserted into the produced woven material. However, this is an expensive and is comparatively slow process; moreover, flat looms are generally more expensive than circular weaving looms.
It is known to produce textile panels of a desired width from circular woven material by cutting the circular woven material open with a continuous longitudinal cut extending parallel to the warp. In this method, all the weft filaments of the circular woven material are separated in one line. It is not possible in this case to produce a Sulzer edge. In order to reinforce the selvages thus produced, the woven material is folded over at the edge and is fastened by a seam or ultrasound welding. However, this frequently applied solution has several disadvantages. To start with, this procedure requires additional material, typically up to 8 percent of the woven material width, thus rendering the production more expensive. A further problem occurs when the produced textile panels are rolled up. Due to doubling of the material thickness at the selvages of the textile panels, handling the produced rolls of textile panels is made harder.
U.S. Pat. No. 7,178,555 describes a method for manufacturing a belt having warp filaments and at least one weft filament, wherein one method step comprises the shrinking of the warp filaments in the central area of the woven material. U.S. Pat. No. 5,851,638 further describes a woven material for reinforcing, or armoring sheet-like structures of weft and warp filaments, forming open spaces with one another. Adjoining a basic woven material is an edge where the weft filaments and/or the warp filaments are reinforced. The purpose of this device is the mechanical reinforcement of the woven material being produced. Furthermore, DE 2 340 817 A1 discloses a method for reinforcing the selvages of woven materials with separate weft filament ends. The above-mentioned forming of a raised edge welt is not recognized in this publication as a problem to be solved.
Another known solution is to weld the exposed warp and weft filaments in the border area with an ultrasound welding device. However, it was found that such a welded border area does not have the required strength, and that the applied welding energy has to be regulated with great precision in order to avoid damaging the woven material.
An additional solution is known from design patent AT 010 526 U1 that proposes the removal or omission of warp filaments from the selvage area during manufacture of the woven material, thus creating a partial-thickness region. By cutting the textile panel along this area, free-hanging weft filaments are created that are folded over the full-thickness region using suitable devices, and are glued to, or welded to the already produced woven material. In this way, a comparatively solid selvage is achieved and the formation of a raised edge when the woven material is rolled up is significantly reduced.
However, it has been found that the selvage areas thus formed are of a strength that is still significantly below that of a Sulzer selvage. Moreover, in practice the handling of free-hanging weft filaments is problematic.